The dye for failure was cast during the Korean War. When American soldiers were locked in lethal combat with hordes of Chinese and their commanders were not allowed to attack their staging and supply sanctuaries in China despite the fact the US has nuclear weapons, many American soldiers died and victory was not achieved. The US never destroyed North Vietnam’s capacity to wage war by placing absurd restrictions on its military commanders. The result was many American deaths and failure. Same pattern today in Iraq and Afghanistan. Caesar and Sherman were both right. Either you wage war or you don’t.
Wars that do not have defined boundaries and placements put in are that way. That is why Iraq and Afghanistan is so hard to put down, simply because resupply and foreign fighters can simply reenter the battlefield. Just as the N. Vietnamese were constantly being supplied from Chinese and Russian support.